DFP-Based Systems:
German Patent No. DE 44 16 881 describes data flow processors (DFPs) in which lines of each edge cell, i.e., a cell at the edge of a cell array often in direct contact with the terminals of the unit, lead outward via the terminals of the unit. The lines do not have any specific function. Instead, the lines assume the function that is written into the edge cells. Several DFPs may be interconnected to form a matrix by connecting all terminals.
Systems with Two- or Multi-Dimensional Programmable Cell Architectures:
In systems with two- or multi-dimensional programmable cell architectures, such as field programmable gate arrays (FPGAs) and dynamically programmable gate arrays (DPGAs), a certain subset of internal bus systems and lines of the edge cells are connected to the outside via the unit terminals. The lines do not have any specific function, and instead they assume the function written in the edge cells. If several FPGAs/DPGAs are interconnected, the terminals assume the function implemented in the hardware or software.
Problems
DFP-Based Systems:
The wiring complexity for peripherals or for interconnecting DFPs is very high, because the programmer must also ensure that the respective functions are integrated into the cells of the DFP(s). For connecting a memory, a memory management unit must be integrated into the unit. For connecting peripherals, the peripherals must be supported. Additionally, cascading of DFPs must be similarly taken into account. This is relatively complicated. Moreover, space in the unit is lost for the respective implementations.
Systems with two- or multi-dimensional programmable cell architectures (FPGAs, DPGAs): The above also applies to FPGAs and DPGAs, in particular when the FPGAs and DPGAs implement algorithms or operate as arithmetic (co)processors.